A carbon–carbon coupling reaction catalyzed by a water soluble rhodium catalyst entrapped in mesoporous silica

A Heck-type reaction, comprising a carbon–carbon coupling between an arylboronic acid and styrene, has been performed using a water soluble rhodium catalyst entrapped in the water-filled pores of mesoporous silica particles. The catalyst-loaded inorganic particles were dispersed in a non-polar medium, either a solution of the reactants in an aromatic solvent (toluene or p-xylene) or a solvent-free mixture of the reactants using a large excess of styrene. The reaction occurred at the oil–water interface, i.e., at the silica pore openings. The yield obtained was higher than that obtained in the conventional liquid–liquid two-phase system. The major advantage with having the catalyst “heterogenized” by entrapment into the siliceous material is the simplicity of the work-up process. The porous particles, containing the catalyst, are simply removed by filtration after completed reaction.